I could speculate about a myriad of reasons for it.
Ron Carey and TDU were directly involved with it.
(Certain) UPS members can cry and bitch all they want.
Great job, on only 22% of the members voting in the "strike authorization".
That's a big hand, to take to the table. (not)
Forcing contracts through with over 50% voting also plays a huge roll. Thank a fat lazy pile of dung for that.